The invention relates to a system unit for a computer comprising at least one plug-in card provided with components and a ventilator for cooling the components, where the system unit is also provided with a controller for setting the ventilator speed as a function of a signal of a temperature sensor.
Siemens catalog ST PCT, issue November 2008, chapter 3 discloses a conventional system unit of a computer. A control input unit, such as a control input unit comprises a keyboard and/or mouse, as well as at least one display device and other hardware units can be connected to this system unit in the form of a so-called “Rack PC”. This system unit is additionally provided with further PCI plug-in cards, and other hardware means, which can be plugged into slots of a motherboard and which are also suited to operate the computer. An airflow generated by a ventilator is provided for cooling the PCI plug-in cards and/or their components, with a controller correspondingly setting the ventilator speed and/or ventilator output as a function of the detected temperature to generate an adequately dimensioned airflow inside the system unit. This known system unit can be integrated, for example, into both a horizontal and a vertical position in a switchgear cabinet or is arranged with a suitable assembly accessory as an Industry Tower PC.
To enable a good cooling effect, irrespective of the position of the system unit, several temperature sensors can be provided, which each detect the respective temperature at its respective location in the system unit and supply the detected temperature to the controller. Here, the controller sets the speed of the ventilator such that the airflow or airflows of the ventilator adequately cool the plug-in cards and/or their components as a function of the detected maximum temperature. It is, however, disadvantageous that a plurality of temperature sensors are needed, where the plurality of temperature sensors have to be arranged at various suitable positions inside the system unit so as to prevent unwanted “hot spots” from forming.
It is known that it is possible to use only one single sensor and to always set the ventilator speed as a function of the detected temperature at a level that is high enough for the cooling to still be adequate, even in cases of a thermally unfavorable installation position. Consequently, however, with this temperature, this ventilator speed is also set in a thermally good installation position. As a result, an increased current requirement occurs, as well as an increased level of noise.